How do I delete the Duolingo app?

Open finder, then music and you should find a file called "iTunes library". Delete this to free up space.

Do the basics again and do something in that language, such as listening to a song in that language. You can always draw common objects and name them in that...

Do something else. Read a book in "your" new language, try to speak to others in that language etc., and after a while start anew with Duolingo.

No, you can access your bookmarks on any device. Because of this, deleting the app won't affect your bookmarks.

Yes. However, you can set consequences for doing this and, if possible, you can also disable app deletion.

You can only delete the weather app if you're in iOS 10. If you are, just tap and hold on it until it starts shaking, and hit the X.

If the app is grey or has a grey box-like figure, try reinstalling then deleting. If that doesn't work, try hard-resetting your phone (Power + Home).

If you want to delete an individual iPhone app, long-press the app and click Remove app.

Press and hold down on the app until an "X" appears in the top left corner. Press the X and the app will be deleted. You can also go into...

If you aren't ever going to do Spanish on Duolingo, then you might as well. Alternatively, you can just disable practice reminders for Spanish in your settings.